Classical vocal sextet miking?

I've got a session tomorrow and Saturday with a classical vocal sextet and am looking for advice in terms of miking them.
The mics I'll be using are a pair of Rode NT5's small diaphragm condensers and pair of Audio Technica AT4040 large diaphragm condensers. The venue is a small church.

The sextet are used to standing in a small semi circle when performing so I am looking to keep this formation.

What would you suggest for mic placement with both pairs of mics to capture both the acoustics and detail of the vocals?

They are after this sound :-

Works of William Byrd, Music from the time of Elizabeth I - YouTube

William Byrd Quomodo Cantabimus Cardinall's Musick Carwood - YouTube

Really would appreciate your advice on this as recording this kind of ensemble is new to me!!

I assume that when you talk about a "session" over two days that this is recording without an audience, so you can position microphones wherever you like without getting complaints about them being in the sightlines.

My feeling is that you are rather constrained if those are the only two pairs of microphones you have at your disposal. The AT4040s are great mics, but they are large diaphragm single-pattern (cardioid), and so have to be positioned with considerable thought about placement and off-axis sound quality. The NT5s, being small diaphragm cardioids, have less of that problem, so could be set up as an X-Y pair just below mouth height at the focus of the semicircle or a little bit back from that. Having positioned the NT5s, I would experiment with placing the AT4040s as an X-Y pair about 2m in front of the singers, above head height and angled down towards them. Arrange a large mat or carpet on the floor between the vocal group and the AT4040s to diffuse reflections.

When it comes to checking the sound at recording, it's important for monitoring that you have a means of delaying the tracks from the NT5s by 3-5ms and then mixing them considerably below the AT4040s so that they are acting as additional clarity. The AT4040s would be the main pair, and their sound should include natural reverb from the building, possibly more than you would care for if they were the only mics.

You can do further work on the level and delay at mixdown, but it will be all to no avail unless you can hear something approaching the final mix on headphones at the test takes before recording proper starts.

Thanks for the replies. The venue is a church with very good acoustics apparently but I've not been there personally. I'm having to travel a fair distance to the session and the vocal group booked a church that they know and think sounds good.

I have a third AT4040 and am wondering if that would be worth bringing?

well, as far as gear goes, I've always gone by the premise that it's better to have it and not use it than it is to need it and not have it... after all, we're talking about a one pound mic here.. not a B3.

Just be conscious that with your LD condensers, you're going to get more of the "room" than you would with dynamics. Pay attention to your ratios, and don't be afraid to move things around to find the sweet spots.

And to bump Boswell's questions... what Pre/Audio I/O and Recorder are you planning on using?

Never leave kit at home! However, what have you planned for monitoring? Headphones really are not suitable, as you can't get an accurate picture of the sound field. Is there a small room that you can set up in that will let you use a small pair of near fields, and then headphones as well? If you monitor in the body of the church, even with good isolation, some of the church sound will leak in.

A good high stand is important, and you can modify the X/Y angle to suit. So first thing I do is let them set up and while they practice move my mic cluster around. You have distance to subject and height to adjust, and to get the balance right, it will mean small movements. Moving the mics up a foot, or back a foot make considerable differences once your ears are 'tuned'.

Church acoustics can work for or against you - in the samples you linked to, the acoustics are good. Not all churches sound like this.

You also need to be a bit of a detective when you hear strange things. Central heating noises, traffic, people moving around, page turns on the music, and watch beeps on the hour. Location recording can be great fun - but tricky. I use some small Edirol powered speakers, and a pair of DT100s. These are horrible to mix on, having a very coloured sound, BUT they're pretty good for revealing noises. Technique wise, explain to the performers that you may need to stop them. Warn them that they need the very best quality, and that you'll be really sorry to do it, but if you hear anything wrong, please don't get cross when I stop you. If warned, they become ok at hearing problems themselves too. Don't let them carry on singing because their voices will go. It's half recording, and half liaison and hand-holding.

In a perfect world, you would have the nt5 pair closer like Boswell stated or better yet an MS pair. Further back again ideally would be a pair of spaced omni mics for the room sound perhaps 14-16 feet high and 20ish feet back from the vocalists. If you could borrow or rent different mics for your second pair you will be better off.

My first reply had suggested initial distances, although without being in the building and hearing the acoustics it's difficult to give specifics. I would start with placing the further pair (the AT4040s in your case) so that you get the overall sound you want, without worrying too much about the detail of the vocal lines. Then place and bring up the closer pair. These could well give enough added detail at a level of 12dB or more below the rear pair - don't overdo this.

With this type of work in this type of venue, I find it's best to record a couple of minutes in each of several mic positions, noting carefully where the mics are at each position. Then stop the performers and listen to the replay, not forgetting to add the appropriate delay in the close pair replay path for each of those positions. Make your judgements based on overall sound (sonic shape of the phrases, amount of building reverb, etc) and clarity of vocal line. The latter will have a lot to do with how well the performers enunciate.

Unless you are able to monitor on your KH120As set up in a smaller room with controlled acoustics rather than in the main church, this is an instance where I would have to trust headphones when listening to replays, making allowances for the fact that these are phones rather than loudspeakers in a studio or domestic listening environment.

To add on to Boswell, if you are being methodical with your mic experiments using his methodology then bring along a roll of tape to mark the floor with the test number. That way when you do your quick review you can quickly reposition the mic stand. Also don't just mark the floor, write on the tape the height of the stand and mic position (ie XY, ORTF, NOS) and angle of inclination towards the singers.

You can use your LDC as a spaced pair even if it isn't ideal but do not limit yourself to what my be "correct" or "ideal" positions. Honestly, the best thing you can do is walk around the room while they are singing moving your head side to side and higher/lower and when your EARS say a spot sounds good then this is where you start with your mic array. If there are several spots just mark them quickly with tape and keep moving until you have several options. Your close SDC array is more limited in position but the same can be done with it as regards height and front to back. Take a small step ladder to help you with this process. With enough experience you will be able to eyeball a room and make some SWAG decisions.

You've already received excellent advice so I'll try not to muddy the waters here. Nobody can give you precise measurements. Look at the arc of the group and visualize a parabolic dish, where would the focal point of that curve be? Start around there. If there's an imbalance, one section to the next, (the sopranos overpowering the bass and baritones for instance) you might have to cheat the mics away from the loudest section. If there's one overly loud voice sticking out on your test recording, you may have to move that person to the back row (or beyond).

One of the beautiful things about using a Rode NT4 for any ensemble, (or the same XY configuration using your NT5s or similar) is that if you are facing the ensemble you should be able to find that sweet spot with your own ears as Jack says. Find a place where you hear all the voices blended evenly - and put the mic stand with the Rode(s) right there. Keep moving and see if you can find a location that's even better.

All the advice offered here is good. Here's another thought, especially in a "live" church with long RT60...If you have access to a stereo microphone such as a Neumann SM2 or SM69, you can set the capsules 90 deg with respect to each other; thereafter, in small increments, vary the height and distance from the performers, arranged in a semicircle, starting with the mic at the focus and both caps set for cardioid. You will find a "sweet spot" where the balance of performers to room ambience is ideal. With the SM2 or SM69, one then can "open up" a little on the variable pattern if needed. Six a capella performers sounds like too small a group to try MS or Blumlein techniques on.

Consider this: A very rough illustration of a typical auditorium (room) could be compared to a stubbed wave guide with width and height dimensions m,n and length L. One surface of this "wave guide" is variable; namely, hard seating, tile floor, carpeted floor and padded seats, or "full house" of people. C is the velocity of sound, which is approximately 340 meters/sec at standard temp and pressure (25 deg C, 760 torr Hg). Theoretically, there are infinite combinations of room "loading" based on the position of the source and the mic. Software packages for acoustic modeling (and treatment) of spaces are available commercially. A complete understanding of the theory requires higher mathematics; check out the late Philip M. Morse's text "Vibration and Sound" for details.

The long and short of this is to experiment. Try the usual "choir loft" location for the singers and the mic. Also try a "corner" where the semicircle of the performers is centered about a room corner, with the mic centered and positioned for best performer to ambience ratio. The room will "behave" differently with corner loading rather than front, center loading. If possible, try the performers at the center of the room with the mic in the focus of the semicircle. One will get a "different" result for each configuration so your ears will tell a lot even before a lot of "glass gets burned".

The only thing I might add to the excellent suggestions above is that sometimes, because of the layout of the church, standing waves cause a problem for the equally spaced pair. Try moving them as a pair several feet to the left or right off of center (and higher is frequently better). What looks to be capturing the room equally may actually be creating problems for your recording. The slight or even more than slight shift sometimes yields better results. As suggested, there is no one right way. I use NT5s regularly and actually like them quite a bit (especially at their price point). I think (because they are quite hot) that you can start with an equilateral triangle in mind (width of the choir to the point of the mics) and work from there. You will probably not go closer than that distance with those mics. Good luck and post links!